With the increasing down-scaling of integrated circuits and increasingly demanding requirements to the speed of integrated circuits, transistors need to have higher drive currents with smaller dimensions. Fin field-effect transistors (FinFET) were thus developed. FinFET transistors have increased channel widths, which channels include the channels formed on the sidewalls of the fins and the channels on the top surfaces of the fins. Since the drive currents of transistors are proportional to the channel widths, the drive currents of FinFETs are increased.
To maximize the channel width of a FinFET, the FinFET may include multiple fins, with the ends of the fins connected to a same source and a same drain. In conventional processes, the formation of multi-fin FinFET include forming a plurality of fins parallel to reach other, forming a gate stack on the plurality of fins, and interconnecting the ends of the plurality of fins to form a source region and a drain region. The interconnection of the ends of the plurality of fins may be achieved through two methods. In the first method, large contact plugs are formed to interconnect the ends of the plurality of fins. In the second method, an epitaxial process is performed to grow a semiconductor material so that the ends of the plurality of fins merge with each other to form block source and drain regions. Source and drain contact plugs are then formed to connect to the block source and drain regions. These methods, however, suffer from high-cost and low-throughput problems.